Two passenger aircraft, a Jetstar A320 and an AirAsia X A330, came alarmingly close to each other while airborne last week near Gold Coast Airport.

The planes came “dangerously close to colliding,” the Sydney Morning Herald reported.

The AirAsia X plane, which had just taken off, is reported to have come within 152 metres of a Jetstar flight that was about to land, causing proximity alarms to sound in both planes’ cockpits.

The minimum vertical separation for major passenger aircraft in Australia is 305 metres.

The Herald said the AirAsia X plane was bound for Auckland and the Jetstar aircraft was arriving from Victoria’s Avalon Airport, near Geelong.

The incident on 21 July 2016 has prompted an investigation by the Australian Transport Safety Bureau (ATSB).

The ATSB stated:

At 1532 Eastern Standard Time on 21 July 2016 the ATSB was notified of an occurrence involving a Jetstar A320 aircraft, and an A330 operated by Malaysian carrier, Air Asia X, that occurred near Gold Coast Airport, Queensland.

The ATSB commenced an investigation on 26 July 2016. As part of this investigation, the ATSB will obtain air traffic control radar and audio information, interview the involved air traffic controllers and flight crews, and gather additional information.

While these aircraft came closer than normal separation standards there was no risk of collision as the systems and the aircraft crews manoeuvred to avoid any further conflict.

At this stage the details of the occurrence are yet to be verified and are limited to the notifications provided by Airservices Australia, Jetstar and Air Asia X.

The ATSB will publicly release an update within the next few weeks on its investigation. The update will outline the facts as we know them at that time.

Aviation observers have criticised the ATSB for downplaying the incident.

“Does the ATSB really expect public interest to be served by not identifying, very early, whether the airliners were directed to fly towards each other in such a dangerous manner, or whether instructions were not followed by one of the aircraft? Or indeed, if some additional unexpected factor contributed to the situation?

“These questions could and should be answered in an interim or preliminary report no later than 30 days after the occurrence of such an incident.”